Low water cut-out



Oct. 24, 1933. w J, MCGQLDRlCK 1,932,382

LOW WATER CUT-OUT Filed June 9. 1932 4 Sheets-Sheet l 4l 46' 44 46 48 47 /9 3/ 69 6o 341kv 49 42 s 35,# 38 5o H 5] 0' Z 40 32 33 93 9075 -39 l 51 55 i 43 9i 76 36 f7 (56 L56 T- g2 96 83 9? F1932 I8 Vj" INVENTOR.

.BWM W( ATTORNEY.

Oct. 24,y 1.933. w. J. McGoLDRicK v 1,932,382

LOW WATER CUT-OUT Filed June 9, 1932 4 Sheets-Sheet 2 INVENTOR.

ATTO E W. J. MCGOLDRICK Oct. 24, 1933.

LOW WATER CUT-OUT 4 Sheets-Sheet 3 Filed June 9, 1932 FUEL SUPPLY A PPA RA Tus INVENTOR.

FUEL. SUPPLY APPnnATUs 60 7a FUEL SUPPLY A PPA Fm Tus.

Oct- 24, 1933- w. J. McGoLDRlcK l 1,932,382

LOW WATER CUT-OUT 4 Sheets-Sheet 4' Filed June 9. 1932 INVENTOR. )MH/fam J/c Gola/rick ATTORNEY.

Patented Oct. 24, 1933 UNITED STATES PATENT OFFICE LOW WATER CUT-OUT Application June 9, 1932. Serial No. 616,345

22 Claims. (Cl. 122-505) llhis invention relates to safety apparatus for boilers and the like and relates particularly to boilers having automatic electrically actuated fuel supplying apparatus and to automatic devices for shutting down the fuel supply whenever the water in the boiler, due to any cause, reaches a predetermined low level.

As is well known, the continued firing of a boiler after the water level therein has reached a certain low level, may result in injury to the boiler and associated apparatus and in some cases wherein the thresher relief apparatus is inadequate may result in an explosion with damage to the apparatus and destruction of property.

Heretofore, varousdevices operating upon the principle of a float, actuated by the attainment of a low water level have been proposed to effect a corresponding control of the fuel supplying apparatus, but such devices have had practical disadvantages whichI have prevented their general use. Among such defects are the response of the devices to fluctuations of water. level, or surges which may occur in the water to violently change its level, and in some cases such heretofore proposed apparatus has been responsive to changes of temperature as well as of water level.

It is therefore an object of my invention to provide an improved apparatus for shutting down the fuel supplying apparatus of a-boiler upon the occurrence of a water level therein to or below a predetermined low level.

Another object of my invention is to provide such an apparatus controlling the fuel supplying apparatus in a manner to prevent subsequently starting up the fuel supplying apparatus until the level of the water has been restored to a level above the said predetermined low level.

Another object is to provide such an apparatus having an improved manual reset feature.

Another object is to provide such an apparatus which, after shutting down the fuel supplying apparatus, must be reset manually before the fuel supplying apparatus can be started up again, and which manual reset cannot be effected until after the Alevel of the water in the boiler has been restored to a level above the predetermined low level.

-Another object is to provide an apparatus for shutting down the fuel supplying apparatus of a boiler which will be actuated by a predetermined low water level independently of temperature conditions. v

Another object of my invention is to provide an electric switch device for boilers fired by electrically actuated fuel supplying apparatus, to

shut down the fuel supplying apparatus upon the occurrence of a predetermined 10W water level in the boiler, and operating in an improved manner.

Another object is to provide such a switch device having improved means to render it nonresponsive to fluctuations or surges of water level in the boiler.

Another object is to provide such an electric switch device having improved means for introducing a time interval between the occurrence of a lower Water level in the boiler and the time of operation of the switch.

Another object is to provide an electric switch device of the class referred to having improved adjusting means. l

Another object is to provide a low water protective device for boilers which Will be relatively inexpensive to manufacture and which will be durable in use and efficient in operation.

Other objects will be apparent to those skilled in the art to which my invention appertains.

My invention is fully disclosed in the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a fragmentary cross-sectional view of a portion of a boiler and illustrating one mode of applying an embodiment of my invention thereto;

Fig. 2 is an elevational sectional View to a larger scale of the embodiment of my invention of Fig. l;

Fig. 3 is an elevational View of the embodiment of Fig. 2 taken from the right hand side thereof;

Fig. 4 is a fragmentary view similar to a part of Fig. 2 illustrating a modification;

Figs. 5, 6, and 7 illustrate electric circuits which I may employ in connection with my invention;

Fig. 8 is an elevation view generally similar to Fig. 3 and illustrating a further modification of my invention;

Fig. 9 is a fragmentary sectional view taken along the lines 9 9 of Fig. 8.

Referring to the drawings, Fig. l, I have shown at 1 the boiler housing and at 2 the water therein. At 3 and 4 are conduit connections communicating with the interior of the boiler. The usual glass tubular water gauge 5 joins the conneotions externally of the boiler, and conduit extensions 6 and 7 communicating with the boiler interior communicate with upper and lower portions of a device indicated generally at 8 and embodying essential features of my invention and which will hereinafter be referred to as a low safety cut-out device.

A pair of electric wires 9 and 10 are brought out from a switch housing 11 of the device 8, one of the wires 9 going to a current supply main 12, and the wire 10 going to the fuel supplying apparatus for the boiler 1, not shown, and a return wire 13 from the fuel apparatus goes to the other supply main 14. A circuit is thus established to the fuel supplying mains through switch contacts in the box 11 and Whenever the water level, indicated at 15, in the boiler 1, reaches a predetermined low level, the said switch contacts will be operated to break the circuit to the fuel supplying apparatus to shut down the same.

The switch contacts in the box 1l can be closed only upon restoring the water level 15 and upon a manual resetting operation performed on the device 8.

The device 8 and its mode of operation to effect the foregoing function will now be described in detail.

Referring to Fig. 2, I have shown at 17 a generally cup-form housing having in the bottom thereof an internally threaded boss 18 whereby connection with the conduit 7 may be effected. 'Ihe upper or open end of the housing 17 has an outwardly extending flange 19; and the housing cover 20 has a corresponding flange 2l whereby, by means of bolts 22, and an annular sealing flange 23, the cover 20 may be vrigidly and sealedly secured on the housing 17 to make a watertight enclosure; and the cover 20 is provided with an internally threaded boss 25 whereby connection with the interior of the housing 17 may be made by the conduit 6.

Upon one side of the housing 17, is a switch box, illustrated at 26, and may comprise side walls 27-27 and top and bottom walls 28 and 29 formed integrally with the outer wall of the housing 17; and a. box cover preferably of sheet metal 30 may be provided for the box and secured on the wall thereof in any suitable or well known manner.

In opposite wall portions of the housing 17, its wall is perforated by a pair of aligned perforations 31 and 32. In the perforation 31 is disposed a shank 33 of a thimble 34, the shank having an axial bore 35 therethrough and on the inner end thereof an outwardly directed ilange 36. A nut 37 on threads 38 of a portion of the shank 33 extending out of the perforation draws the flange 36 rigidly against the inner wall of the housing 17, and the perforation is sealed by a sealing washer 39 between the nut and the housing wall.

In the perforation 32, a thimble 40 is provided, and the flange 41 thereof is supported rigidly uponthe housing 17 in a manner similar to or identical with that for the flange 36; and the thimble 40, however, has an inwardly directed sleeve portion 42 preferably formed integrally with the flange 41, and the bore 43 of the thimble extends through the sleeve 42.

A collapsible bellows 44 of a metal, corrugated wall, generally cylindrical type is provided sealedly perforations in the heads 46 and 48 and the washer 49, and rigidly and sealedly clamps the heads 46 and 48 upon the adjacent end of a rocker arm 5l disposed substantially coaxially of the bellows 47, and extending from the bellows head 48, through the bellows, through the bore 43 and laterallyout of the housing 17.

A pivot pin 52 extends transversely through the wall of the sleeve portion 42 and through the rocker arm 51 and provides a pivot upon which the rocker arm 51 may rock, the axis of the pivot 52 being substantially horizontal and at right angles to the axis of the housing 17.

The bellows heads 46 and 48 have depending, preferably integral, portions 54 and 55 from which extend outwardly laterally a plurality of generally radial arms 56-56 secured at their outer ends as at 57-57 to the inner wall 58 of a cup 59 disposed with its open end upward and below the bellows 44--47 and having its generally cylindrical wall 58 substantially' coaxial with theaxis of the housing 17.

In-the operation of my invention thus far described, Water 2 in the boiler, Fig. 1, stands at a level indicated at 15 and because of communication with the interior of the housing 17 by the connection 3 and conduit 6, water stands at this same level in the housing 17.

The housing 17 is disposed relatively to the boiler so that when the water in the boiler is at a suitable level such as that at 15, water in the housing 17 will stand at a level above the upper end of the cup 59, so'that the cup 59 is normally always fully immersed in water.

If, however, the water level in the boiler falls from the level 15 down to a predetermined low level, not shown, the level will correspondingly fall in the housing 17 and as it recedes below the top of the cup 59, it will leave the cup 59 completely full of water. low water level is reached, the weight of water in the cup 59 will be suiiicient to rock the rocker arm 51 around the pivot 52 and, by means of the end 60 thereof in the switch box 26 will actuate the switch to break -the circuit for the wires 9--10 of Fig. 1 for the purpose described.

By means of the bellows 44 and 47, not only is it possible to project the rocker arm 51 through the wall of the housing without the escape of water or steam through the necessary aperture in the housing wall, but also, the steam pressure which exists at all times within the housing 17, is prevented from exerting longitudinal thrust on the rocker arm 51. To illustrate, a single bellows 47 would suillce to seal the orifice through which the rocker arm 51 extends; but in the absence of the bellows 44, steam pressure on the head 48 of the bellows 47 would exert a very great longitudinal thrust on the rocker arm 51 and cause excessive friction and binding upon the pin 52. By employing the additional bellows 44, the pressure of steam is blocked on' completely from the rocker arm 51 and its associated parts.

Steam pressure upon the heads 46-48 is equalized or balanced.

Again, the downward movement of the cup 59 to effect a rocking of the arm 51 around the pivot 52, is not interfered with by the presence of the bellows 44 and 47, inasmuch as these bellows are flexible in directions at right angles to vthei axes.

Referring to Fig. 2, a block of insulating material is mounted in the box 26. A terminal bracket 66 of metal is secured upon the block 65 as by a rivet 67 and upon an angularly disposed When the predetermined portion 68 at its upper end, a resilient contact arm 69 is riveted and extends transversely across and above the end 60 of the rocker arm 51, and at its over-hanging end carries an electric contact 70 normally engaged with a vertically adjusting mating contact 71 screw-threaded in an angularly extending portion 72 of a terminal plate 73 which is also secured tothe block 65 as by a rivet 74.

The end 60 of the rocker arm 51 has threaded thereupon a sleeve '75 provided with an external annular belt or bead 76 engaging the underside of the switch arm 69. As will now be clear, if the rocker arm 51 is rocked counter-clockwise, it will raise the arm 69 and separate the contacts 70-71. The terminal plates 73 and 66 are electrically connected by a heating wire 77, one end of which is electrically connected to the plate 73 by the head of a screw 78 thereon, and the other end of which is connected to the plate 66 by the head of a screw 79 thereon; and an intermediate portion of the wire 77 is formed into a helical winding 80. An angle portion 81 of the terminal plate 66 supports a contact 82 and a mating contact 83 normally engaged therewith is carried on the end of a resilient switch arm 84, the opposite end of which is riveted to an angle portion 85 of a .terminal plate 86 secured to the block 65 as by rivets 87.

A screw 88 in the terminal plate 73 and a screw 89 in the terminal plate 86 provide connections to which circuit wires corresponding to the wires 9 and 10 of Fig. 1 may be connected.

Any suitable insulated apertures maybe provided in the walls of the box 26 for the wires 9 and l0.

The helical winding 80 surrounds, and is adapted to heat, a heat-conducting rod 90 disposed coaxial therewith, and the heat is adapted to be conducted along the'rod 90 to a portion 91 thereof, projected into a bore of a ratchet wheel 94, and frictionally secured in the bore against rotation by a suitable quantity or coating of solder or other low-fusing metal.

The rod 90 has a knurled extension 93 rigidly secured in a bore 92 of block 65. The ratchet wheel 94 is thus adapted to rotate relative to the rod 90 aixed to the block 65 and thereby permit contacts 82 and 83 to be disengaged in a manner to be hereinafter described.

A ratchet pawl 95 engages teeth of the ratchet 94. and is riveted as at 96 to a plunger 97, the plunger being resiliently constrained to move downwardly by a compression spring 98, one end of which abuts upon the bottom of a recess 99 in the plunger, and the other end of which abuts upon the shank of a screw 100 threaded into the block 65 and projecting outwardly through a slot 101 in the plunger. l

The plunger is provided with a notch 102 normally straddling the resilient switch arm 84.

In the operation of the-switching device just described, current flows in, say, over the wire 9 to the screw 88 and' thence by way of contacts 71--70, switch arm 69, plate 66, contacts 82-83, arm 84, terminal plate 86, and out by way of wire 10.

Upon upward movement of theend 60 of the arm 51 as described, the arm 69 is raised and the contacts 70-71 are separated and thereupon the current flows through the relatively high resistance heating wire '77 from the plate 73 to the plate 66, completing the circuit above described, and the winding 80 begins to heat the rod 90.

If the rod 51 has been rocked due to a falling of the level of water in the boiler to or below the predetermined low level thereof, the arm 51 will stay in its rocked position and current will continue to flow through the wire 77 and it will ultimately heat and melt the solder 93, whereupon the spring 98 will propel the plunger 97 downwardly, rotating the ratchet wheel 94, by the pawl 95 which has heretofore held the plunger' 97 in its upward position.

As the plunger moves downwardly, the notch 102 thereof will engage the switch arm 84 and bend it downwardly separating the contacts 82-83.

Thus, although contact is immediately broken at 70-71, the circuit is not immediately broken but flows temporarily through the wire 77, and after a predetermined time interval required for the solder 93 to melt, the circuit is finally broken at the contacts 82-83.

When the water level in the boiler is fluctuating up and down, or, when due to any cause it surges up and down in the boiler, the corresponding movement of the cup 59 will repeatedly rock the arm 51 and open the contacts 70-71 and reclose them, but such fluctuations are of such short time duration that the time interval of the heating wire 77 will not be passed and the circuit will not be opened.

After the circuit has once been broken at the contacts 82-83, by the downward movement of the plunger 97, it must be closed by a reset upward movement, manually eiected, of the plunger 97, the plunger 97 having a portion 105 projected downwardly through a suitable orifice 106m the lower wall 28 of the switch box 26 for this purpose. But if at the time of resetting the plunger to reclose the contacts 82-83, the water is still below the desired low level, the circuit will still be maintained open at the contacts 70--71 until an additional supply of water is fed into the boiler to raise the level.

Thus as will now be clear, after automatic opening of the circuit by a low' water level, the circuit cannot be again closed until the water level has been raised, and not then unless by manual action.

Of course, as will be understood, upon manual resetting before the required water level has been restored, the contacts 82-83 may remain closed temporarily and current may temporarily flow therethrough and through the heating winding 80 but only for the said predetermined time interval required to again release the plunger and open the contacts 82-83.

In the modification of my invention illustrated in Fig. 4, a form is shown similar to that of Fig. 2 except that instead of the cup 59 of Fig. 2, a. float`200 is provided. The float may be secured to the bellows heads 46 and 48, fragmentarily illustrated, in any suitable way as, for example, by portions of the heads bent at an angle as at 201--201 and secured to theffloat 200 as by screws 202--202. The operation employing a float is substantially the same as that employing the cup 59.

I have shown in Fig. 5 a preferred electric circuit incorporating the switch mechanism of the cut-out and which is in series with the fuel supply of my apparatus. As will be clearly observed in connection with this circuit, if the coil 80 adapted to heat the solder to a point sufficient to permit the plunger 97 to disengage contacts 70-71, were burnt out, the fuel supply apparatus would nevertheless be shut down since the contacts 82 and 83 would remain open even though contacts 70--71 were in circuit closing re- 15 lation. However, since the switch mechanism and coil" are wired in series, with the fuel supply apparatus, the amperage drawn therethrough will fluctuate with the load and consequently the time interval necessary before the plunger 97 will disengage the contacts 70-71 will vary. To correct this condition, a different sized coil is necessary, dependant upon the particular installation and the load requirements thereof.

Fig. 6 illustrates a circuit incorporating the Switch mechanism, wherein the switch mechanism is wired in parallel with the fuel supply apparatus, and consequently is relatively unaffected by variations of load, thereby permitting the same sized coil to be used on varying capacity installations without substantially changing the time interval. In this circuit is is necessary that a relay, generally indicated at 120, and operated by current flowing to the same by a wire 121 leading from the switch mechanism circuit be employed. Leads 122 and 123 from the mains 12 and 14 are adapted to supply current to operate the fuel supply apparatus. The relay 120 is adapted to make or break the fuel supply apparatus circuit and is therefore adapted to operate as a bridge for the leads 122. This particular circuit has the advantage of being unaffected by variations of load, and consequently is adapted to any installation, and in case the coil 80 should burn out for any reason, the fuel supply apparatus will nevertheless shut down when the water drops to a predetermined level due to the fact that the contacts 82 and 83 will be disengaged, thereby breaking the circuit to the relay 120 and causing the fuel supply apparatus circuit to be broken.

Fig. 7 illustrates another circuit which I may employ, wherein the switch mechanism of the low water cut-out and the fuel supply apparatus are wired in parallel with the mains, and a transformer, generally indicated at 125, is employed to permit of a relatively small voltage being used in the switch mechanism. This circuit is particularly adaptable to installations employing a relatively low voltage such as 20 or 25 volts to operate the thermostatic devices such as a room thermostat and any relays required. 'Ihe switch mechanism is connected to the low voltage side of the transformer and is preferably Wired to operate a relay 126 controlling the fuel supply apparatus circuit.

Such a circuit permits the same sized coil 80 to be used in various instalaltions since the amperyage therethrough is uninfluenced by the load under which the fuel supply apparatus is operating. The fuel supply apparatus will be shut down, if, for instance, the coil 80 should burn out, due to the fact that the circuit controlling the relay 126 is broken when the contacts 82 and 83 are disengaged upon the water reaching a predetermined low level. If either of the transformer coils of the transformer 125 should burn out for any reason, no current would flow through the switch mechanism circuit and consequently the fuel supply apparatus would be shut down, since the circuit thereto from the mains 12 and 14 would be broken by the relay 126. Thus, irrespective of whether or not the heating coil 80 or the transformer coils should burn out, the system is rendered absolutelysafe since the fuel supply apparatus cannot continue to operate after a predetermined low level is reached.

The modification shown in Figs. 8 and 9 is generally similar to that described in connection with Figs. 1 to 4 but I employ a modified type of mechanism for supplying heat to the rod which engages the ratchet wheel 94, and which in turn controls the movement of the knockout bar or plunger 97. In this modification, a block of insulating material 140 is secured to the housing 17 as previously described. The block 140 is provided with a bore 141 within which is rigidly aixed a stem l142 of an open-ended cylinder 143. The stem 142 has mounted thereon a ratchet Wheel 94 normally and non-rotatable therewith due to a coating of solder or the like disposed Within the bore of the ratchet wheel 94 as previously described.

The block 140 is provided with a preferably cylindrical shoulder 144 having an internally threaded bushing 145 disposed therein and adapted to threadedly engage a screw 146. The screw 146 engages the U-shaped end of a spring tension member 147 and also the terminal bracket 66. The spring and tension member 147 is adapted to exert pressure against a plunger 148 slidingly mounted in the outer end of the cylinder 143 dependent on the relative rotation of the screw 146.

The plunger or contact 148 has the stem thereof surrounded by a suitable insulating material as indicated at 149 and the interior of the cylinder 143 is insulated with a sheet of mica or the like.

A plurality of carbon discs as indicated at 150 are disposed Within the cylinder and intermediate the bottom thereof and the head of the plunger or contact 148. The stem 142 engages a perfectly flat conducting bar 151 which leads to a terminal 78.

Thus if the contacts 70 and 7l are disengaged, the current will be shunted through the bar 151, thence through stem 142 to the cylinder 143, the carbon discs 150, plunger 148, the spring tension element 147 and the terminal bracket 66. Due to the resistance of the carbon discs 150, the stem 142 Will be heated and after a sufficient time interval will allow the ratchet wheel 94 to rotate as the solder melts, thus allowing the plunger 97 to be forced downwardly breaking the contacts 82 and 83 in a manner and for a purpose previously described. Thus in this modification, the heat is supplied by the resistance of the carbon discs 150 rather than the coil spring 80 and as the discs are forced inwardly against each other, the contacts therebetween will be relatively improved and consequently the resistance and resultant heat 1 will be decreased.

Thus by regulating the tension through screw 146 which is exerted upon contact 148 by the spring tension member 147, the resistance can be relatively altered. The amount of heat required to melt the solder suiciently to permit the ratchet wheel 94 to rotate after a given time interval being substantially constant, the resistance may be altered to provide the requisite amount of heat for varying load conditions or amperage. Such L a construction provides a means of utiliziig the same cut-outs for Widely varying load conditions and yet permit the constant time interval merely by calibrating the resistance to the load requirement by adjustment of screw 146.

My invention is not limited to the exact structure illustrated and described herein, for any changes and modifications may be made other than those set forth hereinbefore without departing from the spirit of my invention, or sacricing its advantages.

A Iclaim:

1. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein under variable pressure, a switch device controlling the apparatus operably responsive to levels of liquid independently of pressure in the housing, and means delaying operation of the switch device at a predetermined liquid level for a time interval.

2. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein under variable pressure, main switch contacts operably responsive to levels of liquid independently of pressure in the housing, auxiliary contacts operable at a predetermined time interval subsequent to the operation of the main contacts.

3. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels establishedtherein under variable pressure, a switch vdevice controlling the apparatus operably responsive to levels of liquid independently of pressure in the housing, means delaying operation of the switch device at a predetermined liquid level for a time interval, and adjustable -means for regulating the time interval.

4. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein under variable pressure, main switch contacts controlling the apparatus operably responsive to levels of liquid independently of pressure in the housing, auxiliary contacts controlling the main contacts, automatic means adapted to operate the auxiliary contacts at a predetermined time interval subsequent to operation of the main contacts, and means whereby a substantially constant time interval may be maintained for varying current strength.

5. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein under variable pressure, a main switch controlling the apparatus operably responsive to levels of liquid independently of pressure in the housing, an auxiliary switch adapted to operate at a predetermined time interval subsequent to operation of the main switch whereby the apparatus circuit will be opened or closed, andV means to adjust the time interval to the apparatus load.

6. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein, a switch device disposed externally of the housing and controlling the apparatus, an auxiliary switch controlling the main switch and adapted to operate at a time interval subsequent to operation of the main switch, a movable element projected through the housing wall operably connected to .the main switch and responsive to levels of liquid in the housing, and a casing substantially enclosing the movable element communicating with the atmosphere and sealedly engaging the housing.

'7. In a liquid level control device for electrically actuated apparatus, a housing adapted to have liquid levels established therein, an electric circuit controlling the apparatus, an element movable responsive to changes of liquid level in the housing and independently of pressure therein, main switch contacts in the circuit controlled by movement of the movable element to be operated upon occurrence of water level below a predetermined level, auxiliary `circuit maintaining contacts and automatic means adapted to operate the auxiliary contacts after the passing of a predetermined time interval following operation of the main contacts.

8. In combination with a boiler, a liquid level `mined time interval following actuation of the main contacts, and manual means for re-setting the auxiliary contacts only when the main contacts are in a position responsive to a restoration of water level above the predetermined level.

9. In combination with a boiler, a liquid level control device for electrically actuated apparatus, an electric circuit controlling the apparatus, an element movable responsive to changes of boiler water level independently of boiler pressure, main switch contacts in the circuit controlled by movement of the movable element to be opened upon occurrence of water level below a predetermined level, auxiliary circuit maintaining contacts and automatic means adapted to operate the auxiliary contacts after the passing of a predetermined time interval following operation of the main contacts, the auxiliary contacts adapted to remain inoperable upon operation of the main contacts responsive to a restoration of water level above the predetermined value, and manual means for operating the auxiliary contacts.

10. In combination with a boiler, a liquid level control device for electrically actuated apparatus, an electric circuit controlling the apparatus, a housing, conduit connections establishing in the housing levels of water in the boiler under boiler pressure, an element in the housing movable responsive to changes of water level independently of boiler pressurein the housing, main contacts in the circuit associated with the housing and controlled by movements of the movable element to be operated upon occurrenceof water level below a predetermined' level, auxiliary circuit maintaining contacts associated with the housing, and automatic means set into operation by opening of the main contacts adapted to operate the auxiliary contacts after the passage of a predetermined time interval following opening of the main contacts.

l1. In combination with a. boiler, a liquid level control device for electrically actuated apparatus, an electric circuit controlling the apparatus, a housing, connections establishing in the housing levels of water in the boiler under boiler pressure, an element in the housing movable responsive to changes of -water level, contacts in the circuit disposed externally of the housing and controlled by movement of the movable element to be opened upon occurrence of water level below a predetermined level, by contact-operating means projected through a perforation in the wall of the housing, and means for sealing the perforation.

12. In combination with a boiler, a liquid level control device for electrically actuated apparatus, an electric circuit controlling the apparatus, a housing, connections establishing in the housing levels of water yin the'boiler under boiler pressure, an element in the housing movable responsive to changes of water level and independently of boiler pressure, main contacts in the circuit disposed externally of' the housing and controlled by movement of the movable element to be opprojected through a perforation in the Wall of the housing, means for sealing the perforation, and circuit-maintaining auxiliary contacts disposed externally of the housing, and automatic means set into operation by opening of the main contacts adapted to operate the auxiliary contacts after the passage of a predetermined time interval following the operation of the main contacts.

13. In a low water safety device for boilers having electrically actuated firing apparatus, an electric circuit controlling the apparatus, a housing, connections establishing in the housing levels of water in the boiler under boiler pressure, an element in the housing movable responsive to changes of water level independently of boiler pressure, main switch contacts in the circuit controlled by movement of the movable element to be opened upon occurrence of water level below a predetermined level, auxiliary circuit-maintaining contacts normally closed, and automatic means adapted to open the auxiliary contacts after the passage of a predetermined time interval following opening of the main contacts, said automatic means comprising a thermally responsive means disposed in the circuit and shunted around the main contacts.

14. In a low water safety device for boilers having electrically actuated firing apparatus, an electric circuit controlling the apparatus, a housing, connections establishing in the housing levels of water in the boiler under boiler pressure, an element in the housing movable responsive to changes of water level independently of boiler pressure, main contacts in the circuit disposed externally of the housing and controlled by movement of the movable element to be opened upon occurrence of water level below a predetermined level by contact-operating means projected through a perforation in the Wall of the housing, means for sealing the perforation, said perforation sealing means comprising a tubular bellows chamber in the housing sealed to the periphery of the perforation at one end and sealed upon a portion of the contact-opening means at the other end, and within the housing.

15. In a low water safety device for boilers having electrically actuated ring apparatus, an electric circuit controlling the apparatus, a housconnections establishing in the housing levels of water in the boiler, an element in the housing movable responsive to changes of water level,

main contacts in the circuit disposed externally of the housing and controlled by movement of the movable element to be opened upon occurrence of water level below a predetermined level by contact-operating means projected through a perforation in the wall of the housing, means for sealing the perforation, said perforation Isealing means comprising a tubular bellows element sealed to the periphery of the perforation at one end and communicating -with the atmosphere through the perforation, sealed to the periphery of a second axially opposite perforation in the housing wall at its opposite end, and communieating with the atmosphere through the second perforation, the contact-operating means comprising an elongated body extended through the first perforation and into the bellows element and Jonnected to the wall of the bellows element internally of the housing, and a sealed connection between an inner end portion of the body portion and the movable element in the housing.

16. In a device of the class described, a housing adapted to be connected to a boiler to establish in the housing levels of Water in the boiler, a movable element in the housing movable responsive to changes of water level therein, a pair of perforations in opposite walls of the housing, a tubular bellows element sealed at opposite ends 'to the housing wall to seal the peripheries of the perforations and communicating interiorly "with atmosphere through the two perforations, an interior portion of the bellows element sealedly connected to the internal movable element, and to an inner portion of an elongated element extending axially through one of the perforations and outwardly of the housing, and pivotally supported by the housing wall, whereby movements of the movable element may be communicated to the external portion of the elongated element, and switch contacts externally of the housing operable by the said externally projecting portion,

17. In a low water safety device for boilers having electrically actuated firing apparatus, a housing, means for connecting the housing to a boiler to establish in the housing levels of Water in the boiler, an element in the housing movable responsive to changes of water level therein, an element projected through the wall of the housing through a perforation therein and internally of the housing connected to the movable element, the external portion adapted to operate a switching mechanism, the switching mechanism comprising a circuit and switch contacts therein adapted to be opened responsive to movement of the movable element in the housing upon the occurrence of a water level below a predetermined low level, auxiliary contacts in serie: with the main contacts, a manual resetting element for the auxiliary contacts spring-pressed in contactopening direction, stop means movable responsive to a predetermined high temperature thereof for normally preventing contact-opening movement of the resetting element, a circuit in parallel to the main contacts comprising a heating element for heating the stop means to the said high temperature upon opening of the main contacts.

18. In a low water safety device for boilers having electrically actuated firing apparatus, a housing, means for connecting the housing to a boiler to establish in the housing levels of water in the boiler, an element in the housing movable responsive to changes of water level therein, Van element projected through the wall of the housing through a perforation therein and internally of the housing connected to the movable element, the external portion adapted to operate a switching mechanism, the switching mechanism comprising a circuit and switch contacts therein adapted to be opened responsive to movement of the movable element in the housing upon the occurrence of a water level below a predetermined low level, auxiliary contacts in series with the main contacts, a manual resetting element for the auxiliary contacts spring-pressed in contactopening direction, stop means movable responsive to a predetermined high temperature thereof for normally preventing contact-opening movement of the resetting element, a circuit in parallel to the main contacts comprising a heating element for heating the stop means to the said high temperature upon opening of the main contacts, and the auxiliary contacts unopened breaking the said parallel circuit.

19. In a low water safety device for boilers, a housing having in-and-out fluid flow apertures for conduit connection with a boiler, an element in the housing movable responsive to changes of water level therein independently of boiler pressure, a pair ofl switch contacts associated with the housing and a circuit controlled thereby, the contacts being operable by movement of the movable element to a predetermined low water level, auxiliary contacts controlling the circuit independently of the first said contact, and automatic means for operating the auxiliary contacts after the passing of a predetermined time interval following operation of the first said contacts.

20. In a low Water safety device for boilers, a housing having in-and-out fluid flow apertures for conduit connection with a boiler, an element in the housing movable responsive to changes of water level therein independently of boiler pressure, a pair of switch contacts associaed with the housing and a circuit controlled thereby, the contacts being operable by movement of the movable element to a predetermined low water level, auxiliary contacts conrolling the circuit independently of the iirst said contact, and automatic means for operating the auxiliary contacts after the passing of a predetermined time interval following operaion of the first said contacts, the operation of the contacts being effected by the movable element in the housing through the agency of an elongated element connected therewith and projected through a sealed aperLure in the housing wall.

21. A low water safety device for boilers operated by an electrically actuated fuel supply apparatus comprising a housing adapted to have levels of Water in the boiler established in the housing, a movable element in the housing under boiler pressure responsive to levels of water therein independently of boiler pressure, an electric circuit having a set of contacts operable by said movable element at a predetermined low water level, auxiliary contacts controlling the circuit independently of the first set of contacts, automatic means for operating the auxiliary contacts after the passing of a predetermined time interval following the operation of the first of said contac s whereby the circuit may be broken, a second independent circuit supplying current to the fuel supply apparatus, and a relay in the second circuit controlling the flow of current therethrough operable by the first circuit whereby when the first circuit is broken the second circuit will be broken.

22. A low water safety device for boilers operated by an elec'rically actuated fuel supply apparatus comprising a housing adapted to have levels of water in the boiler established in the housing under boiler pressure, a movable element responsive to levels of water in the housing independently of boiler pressure, contacts controlling the circuit operable by the said movable element When a predetermined low water level is reached, auxiliary contacts controlling the circuit independent of the first said contacts operable to break the circuit after the passing of a predetermined time interval following operation of the first said contacts, a relay in the circuit, a secondary ccil of a transformer in the circuit and in series wih the said contact and relay, and a second independent circuit supplying current to the fuel supply apparatus controlled by the said relay.

I W. J. MCGOLDRICK.

CERTIFICATE OF CORRECTION.

Patent No. l, 932, 382.

October 24, 1933.

WILLIAM J. McGOLDRICK.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 63, for "a" read the; page 4, line I8, for "is" first occurrence read it; and line 53, for "instalaltions read installations; page 5, line 132, claim l-l, after "level" insert the words independently of boiler pressure; page 7, lines 34 and 35, claim 2l, strike out the words "under boiler pressure" and insert the same after "housing" first occurrence in line 34, of said claimrand that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. v

Signed and sealed this 9th day of January, A. D. 1.934.

(Seal) Actighboggilsirsiner of Patents. 

